The Green Roof Project…

From the outset we knew we needed a shed in our garden. Our garage is already burgeoning so some further storage was desperately required. We also knew that the shed would have to have a green roof. We don’t have a large garden but we try and make as best use of every available inch so by including a green living roof we could accommodate even more flowers in our modest plot.

Construction of the shed started some time ago. We originally posted about it back in September 2011 and whilst the shed has been completed for some time now we’ve only gotten round to writing about it today.

As mentioned in our earlier posting, the shed needed to be bespoke due to the awkward sized corner. We had acquired some very robust Canadian oak pallets which were ideal to provide a strong and sturdy structure necessary to support the weight of a green roof.

The walls were clad in a weatherproof ply skin and then dressed with horizontal softwood slats which have been pressure treated. The roof structure consisted of graded timber roof joists and a double sheeting of marine-grade plywood. Graded timber was then secured around the perimeter of the roof to form a reservoir for the growing medium.

The roof then needed to be waterproofed so a thick visqueen membrane was added and carefully cut to size and pinned to the perimeter timber. At this point we needed to consider how to drain the roof. We were reluctant to install a standard PVC downpipe as, quite frankly, we thought it would look rubbish. We opted instead for a drip-chain arrangement which involved feeding a chain through a pre-drilled hole in the low point of the roof structure. You tie a knot in the chain so it doesn’t fall all the way through the hole and then the chain the drapes down onto the gravel corner of the patio. When it rains, the water finds its way to the hole that the chain passes through and gently trickles down the chain into the gravel beneath. Simple, looks good and is quite the conversation piece too.

You not only require to consider what to do when things are wet but almost as important is what to do when things are dry. There’s not a great deal of growing medium on the roof so it has the potential to dry out pretty quickly. We included a double layer of thick cardboard at the base of the growing medium to hold onto valuable moisture and as we intended to grow alpines on the roof so we filled the roof with a fairly poor mix of topsoil, sand, grit and vermiculite. So that was that, job done. All that was left were the little details…

All at Vialii